http://www.linuxquestions.org/questions/showthread.php?threadid=198896
mkdosfs -F 32 /dev/whatever
で -Fってなに？
http://www.die.net/doc/linux/man/man8/mkdosfs.8.html
- F FAT-size
Specifies the type of file allocation tables used (12, 16 or 32 bit). If nothing is specified, mkdosfs will automatically select between 12 and 16 bit, whatever fits better for the filesystem size. 32 bit FAT (FAT32 format) must (still) be selected explicitly if you want it.
